The present invention relates to a multiple chamber heating unit for heating the ends of thermoplastic tubes.
The German printed patent application 2,136,315 (see also U.S. Pat. No. 3,879,252) describes equipment for applying a sleeve to a tube wherein the end of the tube is heated prior to applying the separately heated sleeve thereto. This known equipment is designed for heating the tube and the sleeve separately and pushing the heated sleeve onto the tube. It was found however, that for speedy and economic operation for example of a press tool which press works the sleeve-reinforced-tube end, one needs several, staggeredly-parallel operating units. Moreover, these units inherently require some clearance for tube insertion and retraction.